Device for changing the number of part streams of a flowing medium

ABSTRACT

A device for changing the number of part streams of a flowing medium comprises a tube (7) with a plurality of holes (11) through the tube wall and a piston (12) displaceable in the tube (7). By means of said piston (12) the interior of the tube can be divided such that a desirable number of holes (11) communicate with a first compartment (13) in the tube intended to be through-flowed by a medium. Through a second compartment (14) in the tube there is extending a piston rod (15) connected with the piston (12). For the change of the number of holes (7) communicating with said first compartment (13), at least one of a determined number of sleeve members (19-21), which are removably applied around the piston rod (15), is arranged to change place on the piston rod between a position within the tube (7) and a position axially outside the tube (7). In the latter position the member is placed between a first stop member (16), which abuts against an end surface of the tube (7), and a second stop member (17), which is arranged to keep the first stop member (16) axially pressed against said end surface. The remaining sleeve members are the same time clamped between the piston (12) and the first stop member (16). The device may be utilized, for instance, at the inlet of a plate evaporator.

The present invention relates to a device for changing the number ofpart streams of a flowing medium, comprising a tube with a plurality ofholes through the tube wall arranged one after the other in the lengthdirection of the tube, a piston, which divides the interior of the tubeinto a first compartment, through which the medium is intended to flow,and a second compartment, which is closed from the first compartment,and a piston rod, which extends from the piston through the secondcompartment and with an end portion extends a distance outside the tube,the number of part streams being determined by the number of holesthrough the tube wall communicating with the first compartment.

In a device of this kind it is desirable to be able to fix the piston ina simple way in different precise positions along the tube without anyneed of providing the device with auxiliary components, and withoutgetting any components left over after an accomplished change.

The object of the present invention is to provide a device for changingthe number of part streams of a flowing medium, which fulfils thisdesire and also has a simple and unexpensive design. All parts of thedevice shall be required for the fixation of the piston in its differentpositions along the tube.

This object can be obtained by a device of the kind initially mentioned,which according to the invention is provided with:

a first stop member, which is arranged axially displaceable on the endportion of the piston rod extending out from the tube and which isadapted to abut against an end surface of the tube,

a second stop member, which is arranged to keep the first stop memberaxially pressed against said end surface of the tube, and

a determined number of sleeve members with different axial extension,which are removably applied one after the other around the piston rodwithin the tube and which together have such an axial extension thatthey serve as spacing means between the piston and said first stopmember, when the latter is pressed against said end surface of the tubeby the second stop member, a change of the number of part streams beingpossible by at least one of the sleeve members being movable to andclampable as a spacing means in a position between the two stop members,and the remaining sleeve members being clampable between the piston andthe first stop member.

A device of this kind has the advantage that all the sleeve members haveto be in place in order that the device will function, regardless of thenumber of part streams determined by the position of the piston relativeto the tube. Even if the device comprises a great number of sleevemembers, there is thus no risk that any of them could get lost.

According to a preferred embodiment of the invention a first compressionspring is disposed between the second stop member and a third stdpmember, which is releasably connected to the end of the piston rod. Bythis, an annular gasket can be placed between the piston and the sleevemember situated next to the piston, which annular gasket under theaction of the force from the first compression spring is radiallyexpandable to sealing between the piston and the tube. Accordingly, theannular gasket should be dimensioned such that in an unexpanded state itwill not counteract a relative displacement between the piston and thetube. By this, it is also avoided that the annular gasket would bedamaged when passing the tube holes, since in its unexpanded state itcan not penetrate into these holes.

The said first compression spring guarantees that the annular gasketslways will be expanded to seal satisfactorily between the piston andthe tube, no matter if the annular gasket after a time of use ispermanently deformed or has changed in dimension because of ageing forinstance.

In a special application of the invention the tube extends throughaligned holes in heat exchange plates, which are releasably heldtogether between a first and a second frame plate. Then the tube holes,which coamunicate with said first compartment of the tube interior, aresituated opposite to every second passage between the heat exchangeplates. The end of the tube nearest the first compartment abuts againsta shoulder, which surrounds a flow channel for the medium through thefirst frame plate and which is united with the latter. Further, acapsule provided with an end wall is telescopically applied on a portionof the tube extending through and out of a hole in the second frameplate, and is releasably connected with the last said frame plate, asecond compression spring being disposed between the end wall of thecapsule and the second stop member.

The number of heat exchange plates may easily be increased or decreased,sine a required corresponding change of the number of holescommunicating with the first compartment of the tube interior is easy toaccomplish. Hereby, it will be possible in an easy way to change thecapacity of a heat exchnger, for instance a plate evaporator, by meansof a device according to the invention.

In a plate evaporator the device according to the invention may beutilized as an inlet device for a liquid to be evaporated, which liquidcan then flow through a channel in one of the frame plates into thefirst compartment of the tube interior.

From there, the evaporation liquid can be conducted into every secondpassage between the heat exchange plates for heat exchanging with aheating medium, for instance steam, flowing in the remaining passagesbetween the heat exchange plates.

The device according to the invention naturally may be utilizedirrespective of the flow direction through the holes in the perforatedtube.

The invention will be explained more closely in the following withreference to the accompanying drawing. In this

FIG. 1 shows a section through the upper part of a plate evaporatorprovided with a device according to the invention, which is adjusted forfour part streams.

FIG. 2 shows a corresponding section through the plate evaporator withthe device adjusted for five part streams.

The plate evaporator shown in FIG. 1 comprises three pairs of heatexchange plates. Each plate pair 1 defines a plate interspace 2constituting a passage for through-flowing of a heating medium, forinstance steam, while the spaces 3 between the plate pairs constituteevaporation passages intended to be through-flowed by liquid to beevaporated. A first and a second frame plate 4 and 5, respectively, keepthe plate pairs 1 together, which seal against each other around theiredges by means of gaskets 6, so that sealed interspaces are formed. Theframe plates 4, 5 as well as the plate pairs have aligned through-holes.A tube 7 is inserted through the holes of the plate pairs via the holein the second frame plate 5 and, further, a distance into the holethrough the first frame plate 4, where it abuts against a shoulder 8,which surrounds a flow channel 9 through the first frame plate 4 forincoming evaporation liquid. An annular gasket 10 is arranged at the endportion of the tube 7 to seal between the tube 7 and the first frameplate 4. The tube 7 has eleven holes 11, four of which being situatedopposite to respective evaporator passages 3.

Within the tube 7 there is arranged a piston 12, which divides theinterior of the tube into a first compartment 13, through whichevaporation liquid is intended to flow to and through the said fourholes 11, and a second compartment 14, which is closed from the firstcompartment 13. A piston rod 15 extends from the piston 12 through thesecond compartment and extends with an end portion a distance outsidethe tube 7. A first stop member 16 is arranged axially displaceable onthe end portion of the piston rod 15 protruding from the tube 7 andabuts against an end surface of the tube 7. A second stop member 17 isalso arranged displaceable on the piston rod 15, and abuts against thefirst stop member 16 between this and the end of the piston rod. Foursleeve members 18-21 of different axial extension are removably appliedone after the other on the piston rod 15 within the tube 7. The sleevemembers 18-21 together have such an axial extension that they serve asspacing means between the piston 12 and the first stop member 16. Thesleeve member 18 situated next to the piston 12 has one of its endsabutting against the piston via an annular gasket 22. The remainingthree sleeve members 19-21 have axial lengths corresponding to multiplesof the distance between adjacent tube holes 11, which are situated withthe same mutual distance along the tube 7 (with the exception of the twofirst holes counted from the left in the drawing). Thus, the secondsleeve member 19 counted from the piston 12 has an axial lengthcorresponding to the distance between two adjacent tube holes 11, thethird member 20 has a length of twice said distance, and the fourthmember 21 has a length of four times said distance. The stop members 16,17 are pressed against the sleeve member 21 and the piston 12 by meansof a first compression spring 23 arranged around the piston rod 15 andabutting against a third stop member 24. The latter is removablyconnected to the end of the piston rod by means of a screw 25 and isformed like an end sleeve surrounding the compression spring 23.

The device further comprises a capsule 27 with an end wall 26telescopically applied on a portion of the tube 7, which protrudes fromthe through-hole of the frame plate 5. The capsule 27 is inserted adistance into said hole to abutment against a shoulder, which surroundsthe hole, via a gasket 28. Near its open end the capsule 27 has a flange29, which is releasably connected with the frame plate 5 by means ofscrews 30. The gasket 28 is radially expanded to seal between the frameplate 5 and the tube 7. Another compression spring 31 is arranged withinthe capsule 27 between its end wall 26 and the second stop member 17.The tube 7 is pressed by the action of the compression spring 31 via thestop members 16, 17 against the shoulder 8, which surrounds the flowchannel 9 through the frame plate 4.

With reference to the FIGS. 1 and 2, it will be described in thefollowing the procedure when the plate evaporator is to be enlarged witha pair of heat exchange plates, i.e. with an evaporation passage.

First the capsule 27 is released from the frame plate 5, whereafter itis removed from the tube 7. The compression spring 31 comes along. Thenthe screw 25 at the end of the piston rod is loosened at least so muchthat the action of the compression spring 23 ceases, so that the annulargasket 22 at the piston 12 becomes unloaded. Now, it will be possible towithdraw the piston rod 15 from the tube, but the piston rod should onlybe withdrawn so much that the sleeve members 19-21 become available. Thescrew 25 at the end of the piston rod is removed, whereafter the endsleeve 24, the compression sprlng 23, the stop members 16, 17 and thesleeve members 19-21 in said order are removed from the piston rod 15.

The third and the fourth sleeve member 20 and 21, respectively, (countedfrom the left in FIG. 1) and the first stop member 16 are remounted insaid order on the piston rod 15, whereafter the second sleeve member 19,the length of which corresponds to the distance between two adjacenttube holes 11, is applied around the piston rod 15. Then, the secondstop member 17, the compression spring 23, the end sleeve 24 and thescrew 25 are mounted, the latter being screwed in just that much thatthe compression spring 23 is still not compressed. The piston rod 15 isthen displaced to such a position in the tube 7, that the first stopmember 16 abuts against the end surface of the tube. In this positionfive tube holes 11 communicate with the first compartment 13 of thetube. The screw 25 now is tightened completely, which means that theannular gasket 22 at the piston 12 expands radially to seal between thepiston 12 and the tube 7. Then, the frame plate 4 is demounted, and afurther pair of heat exchange plates 1A is added to the plate package(see FIG. 2), whereafter the frame plate 4 is remounted.

Alternatively, the second frame plate 5, instead, may be demounted withthe device still connected to it. After connection of a further platepair to the plate package the frame plate 5 is remounted. Thisalternative way of mounting has the advantage that the conduit forcharging evaporation liquid need not be demounted from the frame plate4.

Now the tube 7 can be displaced through the plate package to abutagainst the shoulder 8 around the flow channel 9 (the inlet) in theframe plate 4. By this, each of five tube holes 11 will be situatedopposite to respective evaporation passage 3. Finally, the capsule 27with the compression spring 31 is mounted, whereafter the plateevaporator is ready to be used, now with an increased evaporationcapacity.

In an analogous way the capacity of the evaporator, concerning thenumber of plate pairs, may be changed from three to ten plate pairs bycombination of the sleeve members 19-21 available in the device, so thateach of the tube holes will be situated opposite to an evaporationpassage.

In the drawing the tube holes 11 are shown directed downwards.Preferably, they may also be directed upwards for the achievement of agood distribution of the evaporation liquid already in the uppermostpart of the plate package. In the tube holes there may be mountedreplaceable nozzles, the orifices of which have a chosen size dependenton the kind of liquid to be distributed. If such nozzles have a specialdesign, a good distribution may be obtained even if the tube holes aredirected downwards.

The above described plate evaporator is provided with a device accordingto the invention, by means of which inflowing evaporation liquid isdistributed into a number of part streams. It is also conceivable thatthe device may be used at the outlet of an evaporator to bring partstreams of evaporation liquid from the evaporation passages together toa common outlet.

Also other kinds of plate heat exchangers are conceivable forutilization of the device according to the invention.

What is claimed:
 1. A device for changing the number of part streams ofa flowing medium, comprising a tube (7) with a plurality of holes (11)through the tube wall arranged one after the other in the lengthdirection of the tube, a piston (12), which divides the interior of thetube into a first compartment (13), through which the medium is intendedto flow, and a second compartment (14), which is closed from the firstcompartment (13), and a piston rod (15), which extends from the piston(12) through the second compartment (14) and with an end portion extendsa distance outside the tube (7), the number of part streams beingdetermined by the number of holes (11) through the tube wallcommunicating with the first compartment (13), characterized bya firststop member (16), which is arranged axially displaceable on the endportion of the piston rod (15) extending out from the tube (7) and whichis adapted to abut against an end surface of the tube (7), a second stopmember (17), which is arranged to keep the first stop member (16)axially pressed against said end surface of the tube, and a determinednumber of sleeve members (18-21) of different axial extension, which areremovably applied one after the other around the piston rod (15) withinthe tube (7) and which together have such an axial extension that theyserve as spacing means between the piston (12) and said first stopmember (16), when the latter is pressed against said end surface of thetube by the second stop member (17), a change of the number of partstreams being possible by at least one of the sleeve members (19-21)being movable to and clampable as a spacing means in a position betweenthe two stop members (16, 17), and the remaining sleeve members beingclampable between the piston (12) and the first stop member (16).
 2. Adevice according to claim 1, characterized in that a first compressionspring (23) is disposed between the second stop member (17) and a thirdstop member (24), which is releasably connected to the end of the pistonrod.
 3. A device according to claim 2, characterized in that an annulargasket (22) is disposed between the piston (12) and the sleeve member(18) situated next to the piston, which annular gasket (22) by theaction of the force from the first compression spring is radiallyexpandable for sealing between the piston (12) and the tube (7).
 4. Adevice according to claim 1 characterized inthat the tube (7) extendsthrough aligned holes in heat exchange plates (1), which are releasablyheld together between a first and a second frame plate (4 and 5,respectively), that the tube holes (11), which communicate with the saidfirst compatment (13), are situated opposite to every second passagebetween the heat exchange plates, that the end of the tube nearest thefirst compartment (13) abuts against a shoulder (8), which surrounds aflow channel (9) for the medium through the first frame plate (4) andwhich is united with the latter, and that a capsule (27) formed with anend wall (26) is telescopically applied on a portion of the tube (7),which extends through and out of a hole in the second frame plate (5),and is releasably connected with this frame plate, a second compressionspring (37) being disposed between the end wall (26) of the capsule andthe second stop member (17).